System and apparatus for ionic liquid catalyst regeneration

ABSTRACT

Disclosed are a system and an apparatus for regenerating an ionic liquid catalyst, which has been deactivated by conjunct polymers during any type of reaction producing conjunct polymers as a by-product, for example, isoparaffin-olefin alkylation. The system and apparatus are designed such that solvent extraction of conjunct polymers, freed from the ionic liquid catalyst through its reaction with aluminum metal, occurs as soon as the conjunct polymers de-bond from the ionic liquid catalyst.

FIELD OF ART

The system and apparatus as described herein relate to regeneration ofliquid catalysts. More particularly, the system and apparatus asdescribed herein relate to regeneration of ionic liquid catalysts.

BACKGROUND

Ionic liquids are liquids that are composed entirely of ions as acombination of cations and anions. The most common ionic liquids arethose prepared from organic-based cations and inorganic or organicanions. The most common organic cations are ammonium cations, butphosphonium and sulphonium cations are also frequently used.Pyridinium-based and imidazolium-based cations are perhaps the mostcommonly used cations. Anions include, but are not limited to, BF₄—,PF₆—, haloaluminates such as Al₂Cl₇— and Al₂Br₇—, [(CF₃SO₂)₂N]—, alkylsulphates (RSO₃—), carboxylates (RCO₂—) and many others. The mostcatalytically interesting ionic liquids are those derived from ammoniumhalides and Lewis acids (such as AlCl₃, TiCl₄, SnCl₄, FeCl₃ . . . etc.).Ionic liquids may be suitable, for example, for use as a catalyst and asa solvent in alkylation.

One class of ionic liquids are the so-called “low temperature” ionicliquids, which are generally organic salts with melting points under100° C. and often even lower than room temperature. Another class ofionic liquids is fused salt compositions, which are molten at lowtemperature and are useful as catalysts, solvents, and electrolytes.Such compositions are mixtures of components which are liquid attemperatures below the individual melting points of the components.

Chloroaluminate ionic liquids are perhaps the most commonly used ionicliquid catalyst systems. They are classified as low temperature ionicliquids or fused salt compositions. Alkyl imidazolium or pyridiniumsalts, for example, can be mixed with aluminum trichloride (AlCl₃) toform fused chloroaluminate salts. The use of fused salts of1-alkylpyridinium chloride and aluminum trichloride as electrolytes isdiscussed in U.S. Pat. No. 4,122,245, which is incorporated by referencein its entirety herein. Other patents which discuss the use of fusedsalts of aluminum trichloride and alkylimidazolium halides aselectrolytes are U.S. Pat. Nos. 4,463,071 and 4,463,072, which documentsare incorporated by reference in their entirety herein.

U.S. Pat. No. 5,104,840, which is incorporated by reference in itsentirety herein, describes ionic liquids which comprise at least onealkylaluminum dihalide and at least one quaternary ammonium halideand/or at least one quaternary ammonium phosphonium halide; and theiruses as solvents in catalytic reactions.

U.S. Pat. No. 6,096,680, which is incorporated by reference in itsentirety herein, describes liquid clathrate compositions useful asreusable aluminum catalysts in Friedel-Crafts reactions. In oneembodiment, the liquid clathrate composition is formed from constituentscomprising (i) at least one aluminum trihalide, (ii) at least one saltselected from alkali metal halide, alkaline earth metal halide, alkalimetal pseudohalide, quaternary ammonium salt, quaternary phosphoniumsalt, or ternary sulfonium salt, or a mixture of any two or more of theforegoing, and (iii) at least one aromatic hydrocarbon compound.

Aluminum-containing catalysts are among the most common Lewis acidcatalysts employed in Friedel-Craft reactions. Friedel-Craft reactionsare reactions which fall within the broader category of electrophylicsubstitution reactions and include alkylations.

Other examples of ionic liquids and their methods of preparation arefound in U.S. Pat. Nos. 5,731,101 and 6,797,853 and in U.S. PatentApplication Publication Nos. 2004/0077914 and 2004/0133056. All of thesedocuments are incorporated by reference in their entireties herein.

As a result of use, ionic liquid catalysts can become deactivated, i.e.lose activity, and may eventually need to be replaced. Alkylationprocesses utilizing an ionic liquid catalyst form by-products known asconjunct polymers. These conjunct polymers deactivate the ionic liquidcatalyst by forming complexes with the ionic liquid catalyst. Conjunctpolymers are highly unsaturated molecules and can complex the Lewis acidportion of the ionic liquid catalyst via their double bonds. Forexample, as aluminum trichloride in aluminum trichloride-containingionic liquid catalysts becomes complexed with conjunct polymers, theactivity of these ionic liquid catalysts becomes impaired or at leastcompromised. Conjunct polymers may also become chlorinated and throughtheir chloro groups may interact with aluminum trichloride inaluminum-trichloride containing catalysts and therefore reduce theoverall activity of these catalysts or lessen their effectiveness ascatalysts for their intended purpose.

Deactivation of ionic liquid catalyst by conjunct polymers is not onlyproblematic for alkylation chemistry, but also effects the economicfeasibility of using ionic liquid catalyst as they are expensive toreplace. Therefore, commercial exploitation of ionic liquid catalysts inalkylation is impossible unless they can be efficiently regenerated andrecycled.

Only a few methods for removing conjunct polymers from acidic ionicliquid catalysts in order to regenerate the catalysts have been devised.These methods are described in U.S. Patent Application Publication No.2007/0142213, which document is incorporated in its entirety herein, andinclude, for example, hydrogenation, addition of a basic reagent, andalkylation.

Hydrogenation saturates the double bonds of the conjunct polymers suchthat they release the acidic ionic liquid catalysts. For hydrogenationto occur, hydrogen must either be fed to the acidic ionic liquidcatalyst/conjunct polymer complexes or hydrogen must be produced insitu. This may be done by treating the catalyst containing the conjunctpolymers with a metal in the presence of a Broensted acid whereinteraction between the metal and the acid produces the needed hydrogen.For example, reacting aluminum metal with hydrochloric acid will producehydrogen and aluminum trichloride. Treating the spent catalystcontaining conjunct polymers with Al metal in the presence of enough HClwill produce the hydrogen needed to saturate the double bonds of theconjunct polymers. After hydrogenation, the hydrogenated conjunctpolymers are removed by solvent extraction or decantation and theregenerated ionic liquid catalyst is recovered.

Addition of a basic agent (e.g., amines or ammonium chloride) similarlybreaks up the acidic ionic liquid catalyst/conjunct polymer complexes asthe basic agent forms new complexes with the catalyst. The basic agentmust be carefully chosen so that it is part of the catalyst systemundergoing regeneration. Otherwise, the basic agent will simplydeactivate the catalyst in the same manner as the conjunct polymers.Additionally, the basic agent will react not only with the acidic ionicliquid catalyst/conjunct polymer complexes (e.g., AlCl₃/conjunct polymercomplexes) but also with any unbound cation (e.g., AlCl₃). Therefore,the basic agent must correspond to the basic parent species of cationfrom which the ionic liquid to be regenerated was originally producedand the basic agent must be added in an amount sufficient to react withboth cations bound in the acidic ionic liquid/conjunct polymer complexesand unbound cations. Then the free conjunct polymers are removed and theremaining new complexes are contacted with additional unbound cations(e.g., AlCl₃) to fully regenerate the catalyst. As an example, a usedchloroaluminate ionic liquid may be contacted with butylpyridiniumchloride to provide butylpyridinium tetrachloroaluminate and free theconjunct polymers and then the butylpyridinium tetrachloroaluminate maybe contacted with AlCl₃ to fully restore the catalyst's activity.

However, while effective, each of these methods suffers from certainshortcomings. Thus, to take advantage of the potential of ionic liquidsas catalysts, particularly in alkylation reactions, the industrycontinues to search for an effective and efficient ionic liquid catalystregeneration process.

SUMMARY

Disclosed herein is a system for regenerating an ionic liquid catalystwhich has been deactivated by conjunct polymers comprising: feeding aslurry of aluminum metal and the ionic liquid catalyst into the top of amoveable bed comprised of aluminum metal within a reactor, wherein atleast a portion of the ionic liquid catalyst is bound to conjunctpolymers; feeding a solvent and optionally hydrogen gas into the bottomof the reactor to move upwards through the reactor and into the moveablebed; reacting the aluminum metal with the ionic liquid catalyst in thepresence or the absence of the hydrogen gas in the moveable bed to freethe conjunct polymers from the ionic liquid catalyst; and extracting theconjunct polymers from the ionic liquid catalyst with the solvent toprovide a regenerated ionic liquid catalyst. The system can be used in amethod for regenerating ionic liquid catalyst which has been deactivatedby conjunct polymers.

Also disclosed herein is an apparatus for regenerating an ionic liquidcatalyst which has been deactivated by conjunct polymers comprising areactive extraction column. The reactive extraction column comprises:(a) an upper feed port in the upper end of the reactive extractioncolumn, wherein a slurry of ionic liquid catalyst and aluminum metalenter the reactive extraction column; (b) a lower feed port in the lowerend of the reactive extraction column, wherein a solvent and, if sodesired, hydrogen gas enter the reactive extraction column; (c) amoveable bed comprised of aluminum metal between the upper and lowerfeed ports, wherein the ionic liquid catalyst and the aluminum metalreacts in the presence or absence of hydrogen gas to free conjunctpolymers from the ionic liquid catalyst and some of the freed conjunctpolymers are extracted from the ionic liquid catalyst by the solvent toprovide regenerated ionic liquid catalyst; (d) a lower exit port in thelower end of the reactive extraction column, wherein the regeneratedionic liquid catalyst exits the reactive extraction column; and (e) anupper exit port in the upper end of the reactive extraction column,wherein the solvent and freed conjunct polymers exit the reactiveextraction column.

Among other factors, the system and apparatus disclosed herein are basedon the recent discovery of a novel process, including reaction andextraction steps, to remove conjunct polymers from the ionic liquidcatalyst. The reaction step entails contacting an ionic liquid catalystwith aluminum metal in the presence or absence of hydrogen gas todissociate the conjunct polymers from the ionic liquid catalyst. It hasbeen discovered that this dissociation allows the conjunct polymers tobe thereafter successfully removed from the resulting conjunctpolymer-ionic liquid catalyst mixture by solvent extraction to produce aregenerated ionic liquid catalyst that may be recycled to any process inwhich the catalyst is utilized. However, it has been realized that whenthe conjunct polymers remain in the vicinity of the ionic liquidcatalyst for any appreciable length of time, they re-bond with and againdeactivate the catalyst. Such re-deactivation cannot be tolerated. Thus,the conjunct polymers must be extracted as soon as they are freed fromthe ionic liquid catalyst. The present system and apparatus provide aneffective and efficient means of conducting the novel process so thatthe freed conjunct polymers do not have the opportunity to re-deactivatethe ionic liquid catalyst.

BRIEF DESCRIPTION OF THE FIGURE OF THE DRAWING

The FIGURE of the drawing is a schematic illustration of an apparatus asdisclosed herein for regenerating an ionic liquid catalyst which hasbeen deactivated by conjunct polymers.

DETAILED DESCRIPTION Definitions

The term “conjunct polymer” as used herein refers to a polymericcompound that might bond to a cationic species of the ionic liquidcatalyst by pi bonding or sigma bonding or other means, which results inthe polymeric compound binding to the catalyst, so that it is notremovable by simple hydrocarbon extraction.

As used herein, the term “isoparaffin” means any branched-chainsaturated hydrocarbon compound, i.e., a branched-chain alkane with achemical formula of C_(n)H_(2n+2). Examples of isoparaffins areisobutane and isopentane.

The term “olefin” means any unsaturated hydrocarbon compound having atleast one carbon-to-carbon double bond, i.e. an alkene with a chemicalformula of C_(n)H_(2n). Examples of olefins include ethylene, propylene,butene, and so on.

The term “moveable bed,” as used herein, refers to the fluidic bedformed by the interaction of the ionic liquid catalyst, the solvent, andaluminum metal within the reactor.

A specially designed system and apparatus for conducting a process ofregenerating or re-activating an ionic liquid catalyst, which has beendeactivated by conjunct polymers, are disclosed herein. Basically, thecatalyst regeneration process involves first reacting spent ionic liquidcatalyst with aluminum metal in the presence or absence of hydrogen gasin order to free conjunct polymers from the ionic liquid catalyst andthen extracting the freed conjunct polymers from the catalyst phase witha solvent. Conjunct polymers form during a variety of reactions in whichionic liquid catalysts are employed, for example, alkylation,polymerization, dimerization, oligomerization, acetylation, metatheses,and copolymerization. Conjunct polymers are also by-products of manytypes of Friedel-Crafts reactions, which are reactions that fall withinthe broader category of electrophylic substitution, like alkylation andacylation. The system and apparatus as described herein can beincorporated into an alkylation process whereby isoparaffins (e.g.,isobutane and/or isopentane) and olefins (e.g., ethylene, propylene,and/or butene) react to form low volatility, high quality gasolineblending components.

The term conjunct polymer was first used by Pines and Ipatieff todistinguish these polymeric molecules from the usual polymers. Unliketypical polymers, conjunct polymers are polyunsaturated cyclic,polycyclic and acyclic molecules formed by concurrent acid-catalyzedreactions including, among others, polymerization, alkylation,cyclization, and hydride transfer reactions. Conjunct polymers consistof an unsaturated intricate network of molecules that may include one ora combination of 4-, 5-, 6- and 7-membered rings and some aromaticentities in their skeletons. Some examples of the likely polymericspecies were reported by Miron et al. (Journal of Chemical andEngineernig Data, 1963) and Pines (Chem. Tech, 1982), which documentsare incorporated by reference in their entirety herein. These moleculescontain double and conjugated bonds in intricate structures containing acombination of cyclic and acyclic skeletons.

In practice, conjunct polymers are also called “red oils” due to theircolor and “acid-soluble oils” due to their high uptake in the catalystphase where saturated hydrocarbons and paraffinic products are usuallyimmiscible.

The conjunct polymers deactivate ionic liquid catalysts because theyform complexes with or simply interact with the ionic liquid catalysts.It is believed that complexes form because conjunct polymers, by virtueof their double bonds, form pi complexes with the Lewis acid species inthe ionic liquid catalyst. As an example, conjunct polymers can complexwith AlCl₃, a Lewis acid present in the ionic liquid catalyst1-butyl-pyridinium heptachloroaluminate. Complex formation can weakenthe acid strength of the catalyst, decrease catalyst activity, andeventually render the catalyst ineffective for influencing reactionssuch as an alkylation reaction between isoparaffins and olefins. As aresult, it is believed that catalyst activity is a function of theconcentration of conjunct polymers in the ionic liquid phase wherebycatalyst activity decreases as the concentration of conjunct polymersincreases.

The system and apparatus as described herein are especially suited forconducting the catalyst regeneration process because they perform thereaction step of freeing the conjunct polymers and the extraction stepof removing the conjunct polymers almost simultaneously. It isadvantageous, if not necessary, to react the ionic liquid catalyst tofree the conjunct polymers and subsequently extract the freed conjunctpolymers from the ionic liquid catalyst within a very short period oftime because the freed conjunct polymers can re-bond to the ionic liquidcatalyst if left in the catalyst phase. Such re-bonding or re-complexingis obviously undesirable and defeats the purpose of the catalystregeneration process. But if the conjunct polymers are immediatelyremoved from the catalyst phase, they cannot again deactivate the ionicliquid catalyst. Since the system and apparatus as described hereinpermit extraction the instant the conjunct polymers are freed, thesystem and apparatus can have improved conjunct polymer recovery rates.

The catalyst regeneration system and apparatus as disclosed herein canbe used to regenerate an ionic liquid catalyst used to catalyze any oneof various types of reactions including Friedel-Crafts reactions.However, in one embodiment, the ionic liquid catalyst is used tocatalyze an alkylation reaction between at least one isoparaffin and atleast one olefin.

System

The present system comprises feeding a slurry of aluminum metal and theionic liquid catalyst into the top of a moveable bed comprised ofaluminum metal within a reactor while also feeding a solvent andoptionally hydrogen gas into the bottom of the reactor. These feedscreate a counter-current flow within the reactor. It is important thatat least a portion of the ionic liquid catalyst in the system is boundto conjunct polymers, and, therefore, is deactivated. The solvent andhydrogen, if fed, move upwards through the reactor into the moveablebed, where they meet the slurry of aluminum metal and ionic liquidcatalyst. In the moveable bed of the system, the aluminum metal reactswith the ionic liquid catalyst in the presence or the absence ofhydrogen gas to free (i.e. de-bond) the conjunct polymers from thecatalyst. Thereafter, the system involves extracting the conjunctpolymers from the ionic liquid catalyst with the solvent, which resultsin a regenerated ionic liquid catalyst.

In one embodiment of the system as described herein, the moveable bed issandwiched between a pair of extraction packings. The extractionpackings serve to trap any portion of catalyst and aluminum metal thatescapes from the area of the moveable bed. The portion of the aluminummetal and catalyst that travels to the lower extraction packing has theopportunity to further react in the lower extraction packing. Theportion of the aluminum metal and that travels to the upper extractionpacking has the opportunity to further react in the upper extractionpacking. Thus, the extraction packings can provide an additionalreaction zone and increase the chance of the aluminum metal reacting toextinction thereby reducing aluminum loss.

The step of extracting the conjunct polymers from the ionic liquidcatalyst can take place in only the moveable bed or in both the moveablebed and the extraction packings. When the system does not includeextraction packings, all extraction occurs in the moveable bed. However,when the system includes both the moveable bed and the extractionpackings, a portion of the extraction occurs in the moveable bed and aportion of the extraction occurs in the extraction packings. When theconjunct polymer recovery rate is higher, the extraction step generallytakes place in both the moveable bed and extraction packings.

In the extraction packings, the freed conjunct polymers are extracted bythe solvent such that regenerated catalyst flows from the extractionpackings. The aluminum metal may remain in the extraction packings forfurther reaction or, alternatively, may exit the reactor.

The regeneration system can further include isolating the regeneratedionic liquid catalyst and the solvent, respectively. Once theregenerated ionic liquid catalyst is isolated, it may be returned to theprocess for which it is needed, for example, alkylation. Isolating thesolvent allows for recycling the solvent to the system so that it is notnecessary to constantly feed new solvent to the reactor. However, itshould be appreciated that a certain amount of fresh, make-up solventmay need to be provided to the reactor in addition to the recycledsolvent.

Isolation of the regenerated ionic liquid catalyst may be accomplishedby filtration. Filtering the regenerated ionic liquid catalyst afterextracting the conjunct polymers from it will remove any aluminum metalpresent in the ionic liquid catalyst. Such filtering prevents thealuminum metal from being carried away to and fouling or otherwiseaffecting, due to the presence of solid particles, downstream processunits.

Likewise, filtration of the solvent can lead to isolation of thesolvent. Filtering the solvent and its dissolved conjunct polymers afterextracting the conjunct polymers from the ionic liquid catalyst willremove any aluminum metal present in the solvent-conjunct polymer phase.As stated above, filtering prevents aluminum metal from being carriedaway to and fouling or otherwise affecting, due to the presence of solidparticles, downstream process units.

It is also possible to isolate additional regenerated catalyst from anyresidual solvent-conjunct polymer phase by coalescing (i.e. reverseemulsifying) the solvent-conjunct polymer phase. In the system asdescribed herein, a portion of the ionic liquid catalyst is inevitablyblended with the solvent and its dissolved conjunct polymers. Thiscatalyst-solvent-conjunct polymer mixture is generally in the form of anemulsion. Therefore, coalescing the mixture separates the catalyst fromthe solvent and conjunct polymers. This separated, regenerated catalyst,even if it is only a small amount, can be returned to the process inwhich the catalyst is used. Ionic liquid catalysts are generally quiteexpensive, so this coalescing step is beneficial to the system asdescribed herein and any process in which the catalyst is exploited.

As explained above, the regeneration system extracts the freed conjunctpolymers from the catalyst phase soon after they are de-bonded from theionic liquid catalyst so that they do not have the opportunity tore-bond to the ionic liquid catalyst. Thus, it is extremely beneficialif the step of extracting the conjunct polymers from the ionic liquidcatalyst with the solvent occurs instantaneously after the step ofreacting the aluminum metal with the ionic liquid catalyst.

Apparatus

The present apparatus comprises a single process unit, called a reactiveextraction column, in which both the reaction and extraction steps occuressentially simultaneously.

The reactive extraction column 10 is illustrated in the figure as avertical column. It comprises (1) an upper feed port 2 in the upper endof the column; (2) a lower feed port 6 in the lower end of the column;(3) a moveable bed 5 comprised of aluminum metal between the upper andlower feed ports 2, 6; (4) a lower exit port 11 in the lower end of thecolumn; and (5) an upper exit port 12 in the upper end of the column. Aslurry of ionic liquid catalyst and aluminum metal 1 enter the columnthrough the upper feed port 2, while a solvent and optionally hydrogengas enter the column through the lower feed port 6. The feed ports andexit ports of the column set up a counter-current flow within thecolumn. The slurry of ionic liquid catalyst and aluminum metal 1migrates downward through the column, while the solvent and optionalhydrogen gas migrate upward through the column. All four components meetin the moveable bed 5 where the ionic liquid catalyst and the aluminummetal react in the presence or absence of the hydrogen gas to freeconjunct polymers from the ionic liquid catalyst. The moveable bed 5also facilitates quick extraction of the freed conjunct polymers fromthe ionic liquid catalyst into the solvent as the solvent is present inthe moveable bed 5. Such extraction provides a regenerated ionic liquidcatalyst. The regenerated ionic liquid catalyst 18 then exits the columnthrough the lower exit port 11 and the solvent with its dissolvedconjunct polymers 19 exit the column through the upper exit port 12.

The reactive extraction column may further comprise a pair of extractionpackings, referred to herein as an upper extraction packing 8 a and alower extraction packing 8 b. The extraction packings can be commonlyavailable packings, e.g., structural metal packings or Rasching rings orKoch-Sulzer packings, etc. The purpose of the packing is to increasesurface area for reaction and extraction, increase mixing, and enhanceliquid-liquid mass transfer. The upper and lower extraction packings 8a, 8 b surround the moveable bed such that the moveable bed issandwiched between them. The upper and lower extraction packings 8 a, 8b further facilitate the catalyst regeneration process. The extractionpackings serve two primary purposes.

First, the extraction packings provide a second reaction zone for theionic liquid catalyst and any aluminum metal carried over to them fromthe moveable bed. Catalyst may escape the moveable bed prior to reactionwith the aluminum metal. If so, the unreacted catalyst may be trapped bythe extraction packings where it can react with aluminum metal.Alternatively, aluminum metal may escape the moveable bed. If so, thisaluminum metal may be trapped by the extraction packings where it canreact with and be consumed by deactivated catalyst.

Second, the extraction packings provide an additional extraction zonefor solvent extracting the freed conjunct polymer from the ionic liquidcatalyst/conjunct polymer phase. In a column without extractionpackings, a portion of regenerated ionic liquid catalyst might escapefrom the moving bed prior to extraction thereby allowing any freedconjunct polymer to re-bond with that portion of regenerated ionicliquid catalyst. The extraction packings prevent this problem byproviding an area between the moving bed and the upper and lower exitports where the solvent has an additional opportunity to remove thefreed conjunct polymers.

The reactive extraction column may further include a screen 13 betweenthe movable bed 5 and the lower extraction packing 8 b as shown in thefigure. Since the reactive extraction column 10 is a vertical column,the aluminum metal tends to eventually descend to the lower end of themoveable bed. The screen 13 traps stray aluminum metal that has migratedthrough gravitational effects before it can fall into a pool ofregenerated ionic liquid catalyst 9, which accumulates at the bottom ofthe column.

The apparatus may also further include filters 14 a, 14 b for removingaluminum metal carried over from the column to the regenerated ionicliquid catalyst 18 and the solvent-conjunct polymer phase 19,respectively. A first filter 14 a can be in fluid communication with thelower exit port 11 such that the regenerated ionic liquid catalyst 18passes through the filter 14 a. The filter 14 a traps aluminum metal toprovide an aluminum-free, regenerated ionic liquid catalyst 20. A secondfilter 14 b can be in fluid communication with the upper exit port 12such that the solvent-conjunct polymer phase 19 passes through thefilter 14 b. The filter 14 b traps aluminum metal to provide analuminum-free, solvent-conjunct polymer phase 21. In a reactiveextraction column without extraction packings, the filters 14 a, 14 bare even more important because there are no extraction packings to trapthe aluminum metal and prevent it from traveling to downstream processunits. Aluminum metal collected in the first and second filters 14 a, 14b will eventually be fed into the column for consumption.

Additionally, the apparatus can include a coalescer 15 downstream fromthe second filter 14 b to remove ionic liquid catalyst blended with thealuminum-free, solvent-conjunct polymer phase 21. The coalescer 15 is areverse-emulsifier, which separates the catalyst from thesolvent-conjunct polymer phase. The catalyst 16 is heavier that thesolvent-conjunct polymer phase 17, so it sinks to the bottom of thecoalescer and can be drawn off and returned to the column 10 through arecycle inlet port 22 in the upper end of the column 10. In this manner,no expensive ionic liquid catalyst is wasted and the solvent can besubsequently isolated and re-used in the column.

In one embodiment of the apparatus as described herein, the reactiveextraction column can further comprise a settling zone 3, a first feeddistributor 4, and a second feed distributor 7. The settling zone 3 isan area located immediately below the upper feed port 2, where theslurry of ionic liquid catalyst and aluminum metal 1 settles. The feedthat enters the column through the upper feed port is directed to thefirst feed distributor 4, which uniformly distributes it downwardthrough the column 10 and into the moveable bed 5. Due to its function,the first feed distributor 4 is located below the settling zone 3 andabove the moveable bed 5. While the first feed distributor 4 dispensesthe slurry, its counterpart, the second feed distributor 7 uniformlydistributes the solvent and hydrogen gas, if used, from the lower feedport 6 upwards through the column 10 and into the moveable bed 5. Thesecond feed distributor 7 is located adjacent to the lower feed port 6in the bottom end of the column 10 such that it is above the ionicliquid catalyst pool 9 and below the moveable bed 5. Then, in themoveable bed 5 and the upper and lower extraction packings 8 a, 8 b (ifpresent), the ionic liquid catalyst, aluminum metal, hydrogen gas, andsolvent interact as described above.

Hydrogen

According to the present system and apparatus, hydrogen may be suppliedfrom any source. Hydrogen may be separately supplied from an outsidesource. For example, hydrogen can be bought and transported to thelocation where the regeneration process takes place or hydrogen can besupplied from a separate on-site facility that reforms natural gas intohydrogen using stream reforming processes.

Solvent

Solvent extraction, which occurs in both the system and apparatus asdescribed herein, is a common method of extraction. The solvent can be alow boiling point solvent so that it is easily recovered. Hydrocarbonsolvents function well as solvents in the present system and apparatus.Exemplary hydrocarbon solvents are pentane, hexane, heptane, octane,decane, n-butane, isobutane, isopentane, and mixtures thereof. Thesolvent can be a non-branched hydrocarbon solvent so that side reactionswith the regenerated catalyst are limited.

Aluminum Metal

The aluminum metal can be in the form of, for example, powder (20-75micrometer), pellets (1-3 mm) or aluminum beads (5-15 nm).Alternatively, the aluminum metal can be in the form of granules,sponges, gauzes, wire, rods, etc. Any size and shape is acceptable aslong as sufficient external surface area is available. The aluminummetal may be in (1) macroscopic form, which includes wires, foils, fineparticles, sponges, gauzes, granules, etc. or (2) microscopic form,which includes powders, smokes, colloidal suspensions, and condensedmetal films.

Ionic Liquid Catalyst

Any type of ionic liquid catalyst may be regenerated in the system andapparatus as described herein. Ionic liquid catalysts are well known inthe art. The system and apparatus as described herein can employ acatalyst composition comprising at least one aluminum halide such asaluminum chloride, at least one quaternary ammonium halide and/or atleast one amine halohydrate, and at least one cuprous compound. Such acatalyst composition and its preparation is disclosed in U.S. Pat. No.5,750,455, which is incorporated by reference in its entirety herein.

Alternatively, the ionic liquid catalyst can be a pyridinium orimidazolium-based chloroaluminate ionic liquid. These ionic liquids havebeen found to be much more effective in the alkylation of isopentane andisobutane with ethylene than aliphatic ammonium chloroaluminate ionicliquid (such as tributyl-methyl-ammonium chloroaluminate). The ionicliquid catalyst can be (1) a chloroaluminate ionic liquid catalystcomprising a hydrocarbyl substituted pyridinium halide of the generalformula A below and aluminum trichloride or (2) a chloroaluminate ionicliquid catalyst comprising a hydrocarbyl substituted imidazolium halideof the general formula B below and aluminum trichloride. Such achloroaluminate ionic liquid catalyst can be prepared by combining 1molar equivalent hydrocarbyl substituted pyridinium halide orhydrocarbyl substituted imidazolium halide with 2 molar equivalentsaluminum trichloride. The ionic liquid catalyst can also be (1) achloroaluminate ionic liquid catalyst comprising an alkyl substitutedpyridinium halide of the general formula A below and aluminumtrichloride or (2) a chloroaluminate ionic liquid catalyst comprising analkyl substituted imidazolium halide of the general formula B below andaluminum trichloride. Such a chloroaluminate ionic liquid catalyst canbe prepared by combining 1 molar equivalent alkyl substituted pyridiniumhalide or alkyl substituted imidazolium halide to 2 molar equivalents ofaluminum trichloride.

wherein R═H, methyl, ethyl, propyl, butyl, pentyl or hexyl group and Xis a haloaluminate and preferably a chloroaluminate, and R₁ and R₂═H,methyl, ethyl, propyl, butyl, pentyl, or hexyl group and where R₁ and R₂may or may not be the same.

The ionic liquid catalyst can also be mixtures of these chloroaluminateionic liquid catalysts. Preferred chloroaluminate ionic liquid catalystsare 1-butyl-4-methyl-pyridinium chloroaluminate (BMP),1-butyl-pyridinium chloroaluminate (BP), 1-butyl-3-methyl-imidazoliumchloroaluminate (BMIM), 1-H-pyridinium chloroaluminate (HP), andN-butylpyridinium chloroaluminate (C₅H₅NC₄H₉Al₂Cl₇), and mixturesthereof.

A metal halide may be employed as a co-catalyst to modify the catalystactivity and selectivity. Commonly used halides for such purposesinclude NaCl, LiCl, KCl, BeCl₂, CaCl₂, BaCl₂, SiCl₂, MgCl₂, PbCl₂, CuCl,ZrCl₄, and AgCl as published by Roebuck and Evering (Ind. Eng. Chem.Prod. Res. Develop., Vol. 9, 77, 1970), which is incorporated byreference in its entirety herein. Especially useful metal halides areCuCl, AgCl, PbCl₂, LiCl, and ZrCl₄. Another useful metal halide isAlCl₃.

HCl or any Broensted acid may be employed as an effective co-catalyst toenhance the activity of the catalyst by boosting the overall acidity ofthe ionic liquid-based catalyst. The use of such co-catalysts and ionicliquid catalysts that are useful in practicing the present process aredisclosed in U.S. Published Patent Application Nos. 2003/0060359 and2004/0077914, the disclosures of which are herein incorporated byreference in their entirety. Other co-catalysts that may be used toenhance the catalytic activity of the ionic liquid catalyst include IVBmetal compounds preferably IVB metal halides such as TiCl₃, TiCl₄,TiBr₃, TiBr₄, ZrCl₄, ZrBr₄, HfC₄, and HfBr₄ as described by Hirschaueret al. in U.S. Pat. No. 6,028,024, which document is incorporated byreference in its entirety herein.

Regeneration Conditions

Regeneration, according to the present system or in the presentapparatus, can be carried out at a temperature of 20 to 150° C.Alternatively, regeneration can be carried out at a temperature of 60 to120° C. In general, the temperature will depend upon the type of ionicliquid catalyst and the type of conjunct polymers present. At highertemperatures, the reaction is faster. However, at high temperatures theionic liquid catalyst may begin to decompose. If hydrogen is not used,the pressure can be autogenic. With hydrogen, any pressure necessary togive the advantage of hydrogen can be employed. Any ratio of ionicliquid catalyst to solvent can be employed, for example, 0.5 to 2(vol/vol). At higher ratios, extraction is easier, but more costly. Theresidence time depends upon temperature and the extent of regeneration,but for an alkylation process, the residence time can be 5 minutes to1.5 hours.

It is not necessary to regenerate the entire charge of catalyst from aprocess (e.g. alkylation) in the system and apparatus as describedherein. In some instances, only a portion or slipstream of the catalystcharge is regenerated. In those instances, the portion regenerated canbe the amount necessary to maintain a desired level of catalyst activityin the process that ionic liquid catalyzes.

Although the present system and apparatus have been described inconnection with specific embodiments thereof, it will be appreciated bythose skilled in the art that additions, deletions, modifications, andsubstitutions not specifically described may be made without departingfrom the spirit and scope of the system and apparatus as defined in theappended claims.

1. A system for regenerating an ionic liquid catalyst which has beendeactivated by conjunct polymers comprising: feeding a slurry ofaluminum metal and an ionic liquid catalyst into the top of a moveablebed comprised of aluminum metal within a reactor, wherein at least aportion of the ionic liquid catalyst is bound to conjunct polymers;feeding a solvent and optionally hydrogen gas into the bottom of thereactor to move upwards through the reactor and into the moveable bed;reacting the aluminum metal with the ionic liquid catalyst in themoveable bed to free the conjunct polymers from the ionic liquidcatalyst; and extracting the conjunct polymers from the ionic liquidcatalyst with the solvent to provide a regenerated ionic liquidcatalyst.
 2. A system according to claim 1, wherein the moveable bed issandwiched between a pair of extraction packings, a portion of thealuminum metal and a portion of the ionic liquid catalyst travels to theextraction packings, the extraction step takes place both in themoveable bed and the extraction packings, and further comprisingreacting the portion of the aluminum metal in the extraction packingswith the portion the ionic liquid catalyst in the extraction packings tofree conjunct polymers from the portion of the ionic liquid catalyst inthe extraction packings.
 3. A system according to claim 1, furthercomprising isolating the regenerated ionic liquid catalyst and isolatingthe solvent.
 4. A system according to claim 3, further comprising:filtering the regenerated ionic liquid catalyst after extracting theconjunct polymers from the ionic liquid catalyst to separate a firstportion of aluminum metal present in the ionic liquid catalyst from theionic liquid catalyst; filtering the solvent and the conjunct polymersafter extracting the conjunct polymers from the ionic liquid catalyst toseparate a second portion of aluminum metal present in the solvent andthe conjunct polymers from the solvent and the conjunct polymers; andcoalescing the solvent and the conjunct polymers after extracting theconjunct polymers from the ionic liquid catalyst to remove a portion ofthe ionic liquid catalyst blended with the solvent and the conjunctpolymers from the solvent and the conjunct polymers.
 5. A systemaccording to claim 1, wherein the step of extracting the conjunctpolymers from the ionic liquid catalyst occurs instantaneously after thestep of reacting the aluminum metal with the ionic liquid catalyst.
 6. Asystem according to claim 1, further comprising trapping at least aportion of the aluminum metal within the extraction packings.
 7. Asystem according to claim 1, wherein the solvent is a hydrocarbonsolvent.
 8. A system according to claim 7, wherein the solvent isselected from the group consisting of pentane, hexane, heptane, octane,decane, n-butane, isobutane, isopentane, and mixtures thereof.
 9. Asystem according to claim 1, wherein the ionic liquid catalyst has beenused to catalyze a Friedel-Crafts reaction.
 10. A system according toclaim 9, wherein the Friedel-Crafts reaction is alkylation.
 11. Aprocess according to claim 1, wherein the ionic liquid catalyst isselected from the group consisting of: a first chloroaluminate ionicliquid catalyst comprising a hydrocarbyl substituted pyridinium halideof the general formula A and aluminum trichloride or a hydrocarbylsubstituted imidazolium halide of the general formula B and aluminumtrichloride; a second chloroaluminate ionic liquid catalyst comprisingan alkyl substituted pyridinium halide of the general formula A andaluminum trichloride or an alkyl substituted imidazolium halide of thegeneral formula B and aluminum trichloride; and mixtures thereof,wherein the general formula A and the general formula B are representedby the structures:

wherein R═H, methyl, ethyl, propyl, butyl, pentyl or hexyl group and Xis a haloaluminate, and R₁ and R₂═H, methyl, ethyl, propyl, butyl,pentyl, or hexyl group and where R₁ and R₂ may or may not be the same.12. A process according to claim 11, wherein the first chloroaluminateionic liquid catalyst is prepared by combining 1 molar equivalent of thehydrocarbyl substituted pyridinium halide or the hydrocarbyl substitutedimidazolium halide with 2 molar equivalents of aluminum trichloride. 13.A process according to claim 11, wherein the second chloroaluminateionic liquid catalyst is prepared by combining 1 molar equivalent of thealkyl substituted pyridinium halide or the alkyl substituted imidazoliumhalide with 2 molar equivalents of aluminum trichloride.
 14. Anapparatus for regenerating an ionic liquid catalyst which has beendeactivated by conjunct polymers comprising a reactive extractioncolumn, the reactive extraction column comprising: (a) an upper feedport in the upper end of the reactive extraction column, wherein aslurry of ionic liquid catalyst and aluminum metal enter the reactiveextraction column; (b) a lower feed port in the lower end of thereactive extraction column, wherein a solvent and optionally hydrogengas enter the reactive extraction column; (c) a moveable bed comprisedof aluminum metal between the upper and lower feed ports, wherein theionic liquid catalyst and the aluminum metal reacts to free conjunctpolymers from the ionic liquid catalyst and some of the freed conjunctpolymers are extracted from the ionic liquid catalyst by the solvent toprovide regenerated ionic liquid catalyst; (d) a lower exit port in thelower end of the reactive extraction column, wherein the regeneratedionic liquid catalyst exits the reactive extraction column; and (e) anupper exit port in the upper end of the reactive extraction column,wherein the solvent and freed conjunct polymers exit the reactiveextraction column.
 15. An apparatus according to claim 14, wherein thereactive extraction column further comprises: (f) a lower extractionpacking and an upper extraction packing, wherein the moveable bed issandwiched between the lower and upper extraction packings; and (g) ascreen between the moveable bed and the lower extraction packing to trapstray aluminum metal that has left the moveable bed, wherein a portionof the ionic liquid catalyst and the aluminum metal reacts in the lowerand upper extraction packings to free conjunct polymers from the portionof the ionic liquid catalyst and some of freed conjunct polymers areextracted from the ionic liquid catalyst by the solvent in the lower andupper extraction packings to provide regenerated ionic liquid catalyst.16. An apparatus according to claim 14, further comprising: a firstfilter connected to the lower exit port, wherein a portion of thealuminum metal is separated from the regenerated ionic liquid catalyst.a second filter connected to the upper exit port, wherein a portion ofthe aluminum metal is separated from the solvent and conjunct polymers;and a coalescer downstream from the second filter, wherein a portion ofthe regenerated ionic liquid catalyst that is blended with the solventand the conjunct polymers is separated from the solvent and the conjunctpolymers; and wherein the reactive extraction column further comprises arecycle inlet port in the upper end of reactive extraction column,wherein the regenerated ionic liquid catalyst that exits the coalesceris recycled to the reactive extraction column.
 17. An apparatusaccording to claim 14, wherein the reactive extraction column furthercomprises: (f) a settling zone immediately below the upper feed port,wherein the slurry of ionic liquid catalyst and aluminum metal settlesafter entering the reactive extraction column through the upper feedport; (g) a first feed distributor below the settling zone, wherein thefirst feed distributor uniformly distributes the slurry of ionic liquidcatalyst and aluminum metal from the settling zone into the moveablebed; and (h) a second feed distributor adjacent to the lower feed portin the bottom end of the reactive extraction column, wherein the secondfeed distributor uniformly distributes the solvent from the lower feedport into the moveable bed.